The subjective perception of probability and value is variable, and this variation largely determines risk taking. Recently, efforts have been undertaken to explore these variations in risk taking, and preliminary studies suggest that people are differentially willing to bet on uncertain prospects when the source of uncertainty is their own knowledge rather than random events. It is hypothesized that decision weights and value functions are influenced by the degree of control the decision maker perceives over the probability. At the same time, the illusion of control has become a prominent explanatory construct in the investigation of pathological gambling. Using recent methodological developments, which include advances in modeling decision weights with techniques for eliciting bets on one's own knowledge and abilities, it is hypothesized that factors relevant to value and weighting functions, including perceived control, will be found to contribute to pathological gambling. [unreadable] [unreadable] Four studies will develop methods for quantitatively modeling the impact of control on risk attitude; experimentally test the impact of perceived control on the parameters of weighting and value functions; extend these findings to ecologically valid domains with potential losses; and finally explore whether pathological gamblers differ from typical populations in these factors, and in the impact of control on them. Study 1 will establish methods to investigate weighting and value functions both with and without control, both between and within subjects, and providing performance-contingent monetary incentives. Study 2 will use these methods to experimentally assess the effects of perceived control on the fundamental constructs of value and weighting functions. Study 3 will extend these findings to loss and mixed domains. Study 4 will and assess weighting and value functions in pathological and non-pathological gamblers in a university-based population to assess both static differences between the populations and differences in the impact of control on the weighting and value constructs. [unreadable] [unreadable]